Bottled water enhanced with vitamins—and loaded with sugar—gets low marks from Walter Willett, chair of the Department of Nutrition at Harvard School of Public Health. They are “unequivocally harmful to health,” he told the Washington Post in a February 28, 2012, article on so-called healthy foods that people should avoid.
“Whether vitamins dissolved in water have any benefit will depend on who you are and whether you are already getting enough,” he said. “Some people may be getting too much of some vitamins and minerals if they add vitamin water on top of fortified foods and other supplements.”
The article also referenced a 2011 study by HSPH researchers on how small changes in diet can affect long-term weight gain.